Nickel: The Element

Nickel derives its name from the German word 'nickel', which means 'old nick', an alternate name for the devil. It is also believed to be a shorter version of the German kupfernickel (the mineral niccolite) meaning 'Old Nick's copper'.

Discovery
Swedish chemist, Axel Fredrik Cronstedt, discovered nickel in 1751. He found traces of nickel in the mineral niccolite (NiAs). Niccolite consists of nickel arsenide, NiAs. Nickel arsenide contains 56.1% arsenic and 43.9% nickel. The crystals of NiAs are hexagonal and they occur in a pale copper-red color, with a metallic luster on its surface.

Chemical and Physical Properties
Nickel is a chemical element with the atomic number 28 and atomic weight 58.6934, and is the 24th most abundant element in the Earth's crust. It is generally found in combination with oxygen or sulfur, as oxides or sulfides. The Earth's core is composed of 6% nickel. The electronic configuration of nickel is 1s²2s²2p⁶3s²3p⁶3d⁸4s², with a valence of 0, 1, 2, or 3 electrons. It is placed in the 10th group and the 4th period of the periodic table. Generally it has no specific group name, but it is placed with the transition element such as iron and cobalt.

Nickel is a silvery-white metal that shines brightly on being polished. It is hard, ductile and malleable in nature. Ferromagnetic properties are also exhibited by nickel. Nickel is a fair conductor of heat and electricity. The melting point of nickel is approximately 1453⁰C and its boiling point is 2732⁰C. There are 5 stable and 9 unstable isotopes of nickel.

Uses
Nickel is mainly employed in the production of stainless steel and combined together, both nickel and steel add extra strength to nickel-steel alloys. Invar is an alloy of nickel and steel, and is noted for its low coefficient of thermal expansion. Invar is used to make pendulums and meter scales because it does not contract or expand even in very high or low temperatures. Monel alloy is used to make 'sheet metal' which is highly resistant to corrosion. Its other uses are as follows.

• In desalination plants, nickel is an important element required in the tubing process. Nickel has an excellent ability to resist corrosion. Due to this, nickel is also used in structural work and in electroplating.
• Armor plates are important in defense and police services, using nickel in such jackets and plates makes them more tough and durable.
• Nickel has been a metal widely used in making coins. It forms an important component in nichrome, permalloy and constantin.
• Nichrome is a non-magnetic alloy of nickel and aluminum. Mostly nichrome contains 80% nickel and 20% chromium, by weight. Nichrome is used in fireworks and electric ignition systems. Motorcycle silencers and ceramics are other areas where a nichrome wire is used.
• For hydrogenating vegetable oils, finely divided nickel acts as a catalyst. Hydrogenation is the process used to make vegetable oils for cooking.
• The positive electrode in Edison's storage battery makes use of nickel peroxide, a compound of nickel.
• Nickel forms an important part of nickel-cadmium batteries as well.
• Adding nickel to glass gives a greenish color to it, and so nowadays we can find extensive use of nickel in the glass-making industry.

Occurrence
Nickel is mostly found in meteorites. Its presence in meteorites help scientists in distinguishing it from other minerals. Nickel is commercially extracted from pentlandite and pyrrhotite. Deposits of nickel are mostly found in Ontario, Australia, Cuba and Indonesia.

Health Hazards
We might have experienced that gold rings, earrings and similar ornaments often cause redness, scaling and itching on body parts. The redness or scaling occurs due to a reaction caused by nickel particles when it comes in direct contact with the skin. Watches, jewelry, zippers, eyeglasses, etc. can all contain nickel particles and hence cause contact reactions. Hypoallergenic jewelry is an option for people who wish to wear jewelry but can't wear them due to nickel allergy.

Why is nickel exposure harmful to skin? Exposure to nickel should not exceed 1mg/m³ (calculated for 8 hours per day for over 40 hours per week). Nickel or nickel compounds like nickel sulfate, are just like a germ to the immune system, causing allergic contact dermatitis. Nickel can cause lung inflammation if consumed in large quantities. Nickel belongs to the category of carcinogenic substances and is very poisonous for humans.

Nickel has many advantages in industries but at the same time, its unchecked spread in the environment is harmful to animals, plants and humans. Timely check on the possible threats of this metal can save us from various diseases. Wearing jewelry containing nickel is not advisable as it can lead to skin complications. Use of nickel must be restricted to factories and industries. In this way, we can benefit from this element and also maintain a good health. The price of Nickel keeps fluctuating in the share market and presently it is $8 - $10 lb per USD.